Historic Clinical Trial External Control Arm Provides Actionable GEN-1 Efficacy Estimate Before a Randomized Trial

To inform continued development of the novel immune agent GEN-1, we compared ovarian cancer patients' end points from a neoadjuvant single-arm phase IB study with those of similar historic clinical trial (HCT) patients who received standard neoadjuvant chemotherapy.

Applying OVATION-1 trial (ClinicalTrials.gov identifier: NCT02480374) inclusion and exclusion criteria to Medidata HCT data, we identified historical trial patients for comparison. Integrating patient-level Medidata historic trial data (N = 41) from distinct neoadjuvant ovarian phase I-III trials with patient-level OVATION-1 data (N = 18), we selected Medidata patients with similar baseline characteristics as OVATION-1 patients using propensity score methods to create an external control arm (ECA).

Fifteen OVATION-1 patients (15 of 18, 83%) were matched to 15 (37%, 15 of 41) Medidata historical trial control patients. Matching attenuated preexisting differences in attributes between the groups. The median progression-free survival time was not reached by the OVATION-1 group and was 15.8 months (interquartile range, 11.40 months to nonestimable) for the ECA. The hazard of progression was 0.53 (95% CI, 0.16 to 1.73), favoring GEN-1 patients. Compared with ECA patients, OVATION-1 patients had more nausea, fatigue, chills, and infusion-related reactions.

Comparing results of a single-arm early-phase trial to those of a rigorously matched HCT ECA yielded insights regarding comparative efficacy prior to a randomized controlled trial. The effect size estimate itself informed both the decision to continue development and the randomized phase II trial (ClinicalTrials.gov identifier: NCT03393884) sample size. The work illustrates the potential of HCT data to inform drug development.